1. Field of the Invention
This invention relates to a skid control system for a vehicle having a wheel and a brake for the wheel, and more particularly to a safety device of a skid control system in which skid control operation is stopped on failure of a constituent circuit.
2. Description of the Prior Art
A skid control system is used for a vehicle, by which skid control operation for the wheel is performed to avoid a locked wheel condition and obtain good braking performance on any road. In skid control operation, the brake pressure to the wheel is alternately relieved and reapplied, or relieved, maintained constant and reapplied. When failure occurs in a constituent circuit of a skid control circuit arrangement such as a wheel speed detector, a deceleration signal generator, or slip signal generator, the skid control operation is stopped by a safety device which becomes operative to a failure signal. The vehicle is then changed over from the skid control condition into the normal braking condition.
When the brake fluid pressure of the master cylinder operated by the driver is further higher than the skid-controlled brake pressure to the wheel on the failure of the constituent circuit, the brake pressure to the wheel rapidly rises up immediately after the vehicle is changed over from the skid control condition into the normal braking condition. In that case, there is the fear that the wheel is suddenly locked, the steering of the vehicle is lost, or the behavior of the vehicle becomes disorderly.